Replacing Fuel Tank on 25' Cruiser

[Solesurfer]

Hello,
Firstly, sorry for the size of my pictures, I couldn't figure out how to make them smaller, but bigger gives you more detail I suppose.
I recently noticed about a gallon of gasoline in my bilge. I pulled the cockpit floor/steps and noticed corrosion where the wood stops touched the tank. I disconnected all the hoses which included a vent and fill hose on both starboard and port sides, and the two fuel pickups centered on the tank.

I referenced Anna Leigh's post and it really helped alot. They're approach was to cut the tank and get a retrofit to fit the opening. I wanted to see if I could pull the whole thing out.
http://www.c-brats.com/viewtopic.php?t=18784

I've been in touch with C-Dory and they installed the tank and then built the deck around it. From looking at it, it almost looks like you could wiggle it out, but the fill nozzle on both sides are hitting the lip of the cockpit floor. I had to cut about a 3-4 inch notch into the lip of the cockpit floor so the vent/fill nozzles would clear. This was all under the step area, so I'm hoping I can get away with not building it back up. I also had to cut the wood stops out and noticed what I think is the failure point. The wood stops are glassed over, but the ends are raw wood. The raw wood is flush against the tank and naturally water gets in the bilge and gets trapped which leads to corrosion.

I then was able to get the whole tank out and sitting in the bilge was about 10 gallons of fuel. I got in touch with Coastline Equipment in Bellingham, as they manufactured the original tank and they said they can provide an exact replacement.
Now I just have to clean up the fuel and muck, scrub everything until it's white again.

Once I get the tank I plan to primer and epoxy it. I've heard about people putting a layer of fiberglass after that, but I'm wondering how much thicker it will make the tank, as the opening is pretty tight as it is.

I wanted to post about my experience so that someone else might find it useful.
If anyone can lead me in the direction on how to create an album on c-brats that would be much appreciated.

 

[thataway]

The best way to preserve the new tank is to clean scratch the surface with 80 grit, wipe with acetone and coal tar epoxy. Fiberglass should not be necessary. There was no coating on the original tanks (rarely are). You are right that the wood caused the problem--even worse if the wood was treated--which it may have been.

David Pascoe (ref in the linked post Anna Leigh's) is the best recommendation I have seen ref the tanks

Never allow water absorbent material such as wood to come in contact with the tank.
Do not use rubber strips: rubber contains carbon, which is cathodic to aluminum and will cause galvanic corrosion.
It is best to use only stainless steel pipe fittings for the fuel supply. Do not mix a variety of metals. Do not use steel or galvanized.
Make sure that wherever the tank is sitting on is a stable surface; always use the hull stringers and never the bottom of the hull.
Make sure that straps or whatever securing devices you use don't cause crevice corrosion.
Tank should not be so deep in bilge that its going to be in constant contact with bilge water.

In the case of the 25, the tanks need to be kept out of the water as much as possible. (best if 100% out of water), The tank should be supported (see Pascoe), and air allowed to circulate around.

I have glassed a fuel tank--but it was in an open boat where the bottom of the tanks had some pin holes. I cleaned the tank, put gravel and water inside and tumbled it to rough up the bottom, washed with Acetone--and then poured a layer of epoxy on the inside of the tank. I had also prepped the outside of the tank, so that as soon as the epoxy was in the gel stage inside, I put my first layer of epoxy on the outside, and then wrapped with glass cloth. I sold the boat 12 years later--and the tank was still doing fine. Again--this was in the open, not in a bilge.

 

[localboy]

see Pascoe)

Dr Bob, what does this mean?

Solesurfer, we have an '07 and I dread this. Thanks for the pics etc. I hope I never have to, but I imagine I may....

 

[South of Heaven]

Wow, nice job and thanks for the pictures. I was under the impression that the tank was slightly elevated and never was touching the bottom....

Maybe I didn't see this, but where was the fuel leaking from?

When I removed my cockpit sole on my old 25 the tank looked good except for some dirt on top of it. We never removed the tank to check the bottom. Hmmm. I also had that issue with rot on the steps where the fuel fill is. My boat was an 07, similar to yours.

 

[thataway]

see Pascoe)

Dr Bob, what does this mean?

Solesurfer, we have an '07 and I dread this. Thanks for the pics etc. I hope I never have to, but I imagine I may....

It refers to the link which was above (David Pascoe). He outlines in his on line article how to properly support and secure aluminum fuel tanks.

 

[Solesurfer]

Wow, nice job and thanks for the pictures. I was under the impression that the tank was slightly elevated and never was touching the bottom....

Maybe I didn't see this, but where was the fuel leaking from?

When I removed my cockpit sole on my old 25 the tank looked good except for some dirt on top of it. We never removed the tank to check the bottom. Hmmm. I also had that issue with rot on the steps where the fuel fill is. My boat was an 07, similar to yours.

I have yet to get into cleaning everything, but I believe it corroded on the front side of where the wood blocks were.

I also noticed right before the sun went down that it appears the tank was supported by plastic strips. It wasn't properly supported and I think there might be more corrosion on the bottom.

 

[Solesurfer]

The best way to preserve the new tank is to clean scratch the surface with 80 grit, wipe with acetone and coal tar epoxy. Fiberglass should not be necessary. There was no coating on the original tanks (rarely are). You are right that the wood caused the problem--even worse if the wood was treated--which it may have been.

David Pascoe (ref in the linked post Anna Leigh's) is the best recommendation I have seen ref the tanks

That's a really good article. However I'm a little apprehensive to gluing the tank to the hull with 5200. I can only imagine the headache if you had to remove the tank again for whatever reason. If you can't get access to where the 5200 is you probably just need to cut the tank out.
With Anna Leigh's experience, it looks like they glassed in spacers and just set the new tank on top.


I'm wondering if this will be enough to keep the tank in place especially with the weight of the fuel sloshing around. Or should it be braced(not with raw wood!) on the sides/one side to keep it set in place?

 

[smckean (Tosca)]

I now own the Anna Leigh (re-christened "Tosca"). I have not had problems with the replacement tank (yet, anyway..... :wink. I have no way of knowing if a problem has developed under that deck, but I smell and hear nothing unusual.

The one problem I did have resulted from the re-fashioning of the steps required in order to accommodate the filler pipe etc after the tank was replaced. Those steps were not fastened down very well and eventually worked loose and became a leak point. This was particularly problematical because the leaking water found its way into multiple places in the cabin via a channel molded into the hull; therefore, it was very difficult to diagnose the source of the leak. Removing the steps, providing adequate mounting brackets, and re-caulking totally solved the problem.